/* Copyright (c) 2013, Cornell University
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *     * Redistributions of source code must retain the above copyright notice,
 *       this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of HyperDex nor the names of its contributors may be
 *       used to endorse or promote products derived from this software without
 *       specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

package org.hyperdex.client;

import java.util.LinkedList;
import java.util.Queue;

public class Iterator implements Operation
{
    private long ptr = 0;
    private Client c;
    private Queue<Object> backlogged;

    public Iterator(Client c)
    {
        this.c = c;
        this.backlogged = new LinkedList<Object>();
        _create();
    }

    protected void finalize() throws Throwable
    {
        try
        {
            destroy();
        }
        finally
        {
            super.finalize();
        }
    }

    public synchronized void destroy()
    {
        if (ptr != 0)
        {
            _destroy();
            ptr = 0;
        }
    }

    /* ctor/dtor */
    private native void _create();
    private native void _destroy();

    /* Other calls */
    public Boolean hasNext() throws HyperDexClientException
    {
        while (!finished() && backlogged.isEmpty())
        {
            this.c.loop();
        }

        return !backlogged.isEmpty();
    }

    public Object next()
    {
        return backlogged.poll();
    }

    private native boolean finished();
    public native void callback();

    /* Utilities */
    private void appendBacklogged(Object ret)
    {
        backlogged.add(ret);
    }
}
